Conception (when the egg is fertilized by the sperm) can take place as soon as three minutes after sex or it may take up to five days. Implantation (when the fertilized egg attaches to the uterine wall) occurs five to 10 days after fertilization—which means it can happen anywhere from five to 15 days after you had sex.

Does pregnancy start at conception or implantation?

A pregnancy starts with fertilization, when a woman's egg joins with a man's sperm. Fertilization usually takes place in a fallopian tube that links an ovary to the uterus. If the fertilized egg successfully travels down the fallopian tube and implants in the uterus, an embryo starts growing.

What week does conception begin from?

Pregnancy begins when a sperm fertilizes an egg. This usually occurs in the 2 weeks following the first day of the most recent menstrual period.